Method for heating a catalytic converter

Patent metadata

Field	Value
Publication number	US-11913396-B2
Application number	US-202218247819-A
Country	US
Kind code	B2
Filing date	Mar 31, 2022
Priority date	Apr 26, 2021
Publication date	Feb 27, 2024
Grant date	Feb 27, 2024

Abstract

A method for heating a catalytic converter includes a) switching on a compressor; b) at least partially opening an injection valve; c) setting a combustion-air/fuel ratio of λ<1 in combustion chambers; d) detecting an actual value of the oxygen content in the exhaust gas; and e) comparing the actual value with a target value, where the target value corresponds to an exhaust-gas oxygen content that would be set in a region of the catalytic converter if the combustion-air/fuel ratio in the combustion chambers is approximately λ=1, where a manipulated variable output by a controller on a basis of a deviation of the actual value from the target value is kept constant when the actual value reaches one of two limit values of a value range within which the target value is ranged, and where the two limit values deviate from the target value by approximately 3%.

First claim

The invention claimed is:

1. A method for heating a catalytic converter ( 48 ) which is disposed in an exhaust system ( 44 ) of a spark-ignition internal combustion engine ( 10 ), wherein a control unit ( 68 ) outputs a respective manipulated variable to an electrically driven additional compressor ( 20 ) and to at least one injection valve ( 52 , 54 ), wherein as a result of the at least one injection valve ( 52 , 54 ) being at least partially opened, air compressed by the electrically driven additional compressor ( 20 ) is introducible into the exhaust system ( 44 ) downstream of exhaust valves of the spark-ignition internal combustion engine ( 10 ) which are assigned to respective combustion chambers ( 12 ) of the spark-ignition internal combustion engine ( 10 ), and wherein signals from at least one oxygen sensor ( 64 , 66 ), via which an oxygen content in exhaust gas fed to the catalytic converter ( 48 ) is detected, are supplied to a controller ( 72 ) of the control unit ( 68 );
the method comprising the steps of:
a) switching on the electrically driven additional compressor ( 20 );
b) at least partially opening the at least one injection valve ( 52 , 54 );
c) setting a combustion-air/fuel ratio of λ<1 in the combustion chambers ( 12 ) of the spark-ignition internal combustion engine ( 10 );
d) detecting an actual value ( 128 , 134 ) of the oxygen content in the exhaust gas by the at least one oxygen sensor ( 64 , 66 ); and
e) comparing the actual value ( 128 , 134 ) with a target value ( 114 ) of the oxygen content, wherein the target value corresponds to an exhaust-gas oxygen content that would be set in a region of the catalytic converter ( 48 ) if the combustion-air/fuel ratio in the combustion chambers ( 12 ) of the spark-ignition internal combustion engine ( 10 ) is approximately λ=1, wherein a manipulated variable ( 90 , 106 ) output by the controller ( 72 ) on a basis of a deviation of the actual value ( 128 , 134 ) from the target value ( 114 ) is kept constant when the actual value ( 128 , 134 ) reaches one of two limit values ( 122 , 124 ) of a value range ( 120 ) within which the target value ( 114 ) is ranged, and wherein the two limit values ( 122 , 124 ) of the value range ( 120 ) deviate from the target value ( 114 ) by approximately 3%.

2. The method according to claim 1 , wherein a speed of the electrically driven additional compressor ( 20 ) is pilot-controlled and wherein an opening width of the at least one injection valve ( 52 , 54 ) is adjusted in such a way that the target value of the oxygen content in the exhaust gas is set.

3. The method according to claim 1 , wherein an opening width of the at least one injection valve ( 52 , 54 ) is pilot-controlled and wherein a speed of the electrically driven additional compressor ( 20 ) is controlled in such a way that the target value of the oxygen content in the exhaust gas is set.

4. The method according to claim 1 , wherein the steps a) to e) are carried out following a cold start of the spark-ignition internal combustion engine ( 10 ).

5. The method according to claim 1 , wherein the steps a) to e) are carried out when a speed of the spark-ignition internal combustion engine ( 10 ) exceeds a threshold value of 100 revolutions per minute.

6. The method according to claim 1 , wherein the catalytic converter ( 48 ) is operated as a three-way catalytic converter.

7. The method according to claim 1 , wherein the controller ( 72 ) is a proportional-integral controller.

8. The method according to claim 1 , wherein in step c), in addition to the setting, an ignition instant of a spark plug ( 14 ) assigned to the respective combustion chamber ( 12 ) of the spark-ignition internal combustion engine ( 10 ) is shifted to an instant that is later in time than in normal operation of the spark-ignition internal combustion engine ( 10 ).

Assignees

• Mercedes Benz Group Ag

Inventors

• Schaible Andreas
• Schober Andreas
• Lehmann Hans-Georg
• Schilling Markus

Classifications

• F02D41/0255 Primary

  to accelerate the warming-up of the exhaust gas treating apparatus at engine start · CPC title

• F02D41/1454

  the characteristics being an oxygen content or concentration or the air-fuel ratio · CPC title

• F02D41/0007

  for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12) · CPC title

• F02B37/168

  into the exhaust conduit (F02B37/166 takes precedence) · CPC title

• F01N3/22

  Control of additional air supply only, e.g. using by-passes or variable air pump drives · CPC title